A variety of devices place conflicting demands on a battery. Implantable cardioverter defibrillators (ICDs) are an example of a device that place conflicting demands on a battery. For instance, an ICD needs a battery that can provide high rate performance when the ICD detects an arrhythmia. In response to detecting the arrhythmia, the ICD uses the battery to quickly charge capacitors. The energy from these capacitors is used to deliver a defibrillation shock to the patient. Defibrillation shocks are repeatedly delivered to the patient until the arrhythmia is no longer detected. The same ICD also needs a battery that can provide low rate performance. For instance, an ICD must continuously sense and monitor the condition of the heart and provide continuous or intermittent pacing. These monitoring and pacing functions draw low to medium current but require high capacity. As a result, there is a need for a battery that can provide both high rate and low rate/high capacity performance capabilities.